KR101804711B1 - Composition for activating glassy surface layer of slag powder - Google Patents

Abstract

The present invention relates to a furnace slag fine powder stimulant composition and a furnace slag cement used by mixing the same. The furnace slag fine powder stimulant composition according to the present invention is mixed into a range of 65-73 wt% of dodeca calcium hepta aluminate, 5-12 wt% of anhydrous plaster, 3-8 wt% of tartaric acid, and 15-22 wt% of ethylenediaminetetraacetic acid (EDTA). The present invention can increase the activity of furnace slag fine powder.

Description

Technical Field [0001] The present invention relates to a slag fine powder glass composition,

TECHNICAL FIELD The present invention relates to civil engineering and building materials, and more particularly, to a slag fine powder activator composition for increasing the activity of slag by adding it to cement containing blast furnace slag as a main component.

Reducing greenhouse gases as a countermeasure against global warming continues to be an issue. As international agreements such as the Kyoto Protocol and the International Climate Change Negotiations are strengthened, Korea is also aggressively targeting its greenhouse gas reduction targets. There are various kinds of greenhouse gases, but the actually regulated gas is carbon dioxide.

The cement industry is a representative carbon dioxide emission industry and occupies a very important position in the reduction of greenhouse gases. In other words, cement is a material made by calcining limestone and generates a large amount of carbon dioxide during the calcination. It is estimated that approximately 870 kg of carbon dioxide is emitted to produce one ton of cement. Carbon dioxide emissions from cement manufacturing account for about 7% of all greenhouse gas emissions in the Republic of Korea.

Therefore, efforts have been actively made to replace cement with fly ash or blast furnace slag in the cement industry or civil engineering and building materials industry. Particularly, the use of fly ash and blast furnace slag is becoming more popular because it is to recycle industrial byproducts.

However, blast furnace slag has limitations in hydration reaction activity.

Blast furnace slag powder is produced by pulverizing by-products generated in the steel industry when producing pig iron, and rapidly quenched at a high temperature of about 1,500 ° C. When the blast furnace slag is quenched, water is mainly used. In this process, a glassy film is formed on the surface of the blast furnace slag fine powder. Or even if no coating is formed on the surface of the blast furnace slag, a blast furnace film is formed when blast furnace slag is mixed with water and kneaded with concrete or mortar.

 The glassy coating prevents the calcium, aluminum and the like in the blast furnace slag powder from reacting directly with water to hydrate, so that the blast furnace slag powder has latent hydraulic properties which react only in an alkali environment to generate hydrates. Therefore, in order to use blast furnace slag as a substitute for cement, an alkali stimulant capable of breaking glassy coating is needed. As shown in FIG. 1, the alkali stimulant may elute components such as calcium and aluminum present in the blast furnace slag fine powder so that the blast furnace slag fine powder causes a hydration reaction such as cement.

For this reason, the blast furnace slag cement has a problem that the initial compressive strength is low.

The present invention relates to a blast furnace slag fine powder activator composition capable of removing a vitreous coating formed on the surface of a blast furnace slag fine powder and preventing the formation of a glassy coating to increase the activity of the blast furnace slag fine powder and a blast furnace slag Cement composition for use in the present invention.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

In order to achieve the above object, the present invention provides a blast furnace slag powder composition comprising 65 to 73% by weight of dodeca calcium hepta aluminate, 5 to 12% by weight of anhydrous gypsum, 3 to 8% by weight of tartaric acid and 15 to 22% by weight of EDTA %. ≪ / RTI >

The powder of the dodeca calcium hepta aluminate is in the range of 2,000 to 3,000 Cm ² / g, and the content of Al ₂ O ₃ in the dodeca calcium hepta aluminate is preferably 85 to 95% by weight Do. When dodeca calcium hepta aluminate is dissolved in water, it is preferable to have an alkalinity degree enough to maintain a pH of 11-13.

The powder of EDTA is in the range of 10,000 to 20,000 Cm ² / g, and the solubility in 100 g of water is preferably 50 g or more.

In one embodiment of the present invention, the tartaric acid and EDTA are liquid, and the anhydrous gypsum and dodeca calcium heptaaluminate can be formed into a powder.

Meanwhile, the blast furnace slag cement composition according to the present invention is characterized in that it contains cement containing blast furnace slag fine powder, ordinary portland cement, and blast furnace slag fine powder composition for improving the activity of the blast furnace slag fine powder.

According to the present invention, the blast furnace slag fine powder is blended in a range of 40 to 60 wt%, and the blast furnace slag blast stimulant composition can be blended in a range of 3 to 10 wt%.

It can be seen that the blast furnace slag fine powder stimulant composition according to the present invention and the blast furnace slag cement using the blast furnace slag cement according to the present invention have a higher compressive strength, particularly the initial compressive strength, as compared with the general blast furnace slag cement without the use of the irritant composition.

These results indicate that the four components of the irritant composition according to the present invention, i.e., dodecaheptaaluminate, anhydrite, tartaric acid and EDTA, inhibit the formation of the blast furnace slag film itself, slow down the reaction rate, And to form a water channel.

The use of the irritant composition according to the present invention is economical but it is expected that the blast furnace slag fine powder which is used as the main material of the cement binder due to the decrease in the initial compressive strength can be used more positively.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

Fig. 1 is a schematic view showing the removal of the coating film of the blast furnace slag fine powder.
The drawings are to be regarded as illustrative only for the understanding of the technical idea of the present invention, and the scope of the present invention is not limited thereby.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

Hereinafter, the blast furnace slag micropowder irritant composition according to the present invention will be described in more detail.

Blast furnace slag and composed mainly of SiO₂, Al ₂ O₃, CaO, MgO, and and they account for about 96% of the component, and in addition contain small amounts of MnO, FeO, such as TiO₂ and the sulfur and an alkali (Na₂O, K₂O) have. Blast furnace slag has almost the same chemical composition as cement, but chemical reaction also reacts similar to hydration reaction of cement. However, the hydration reaction of blast furnace slag has the characteristic of "potential hydraulicity" which is somewhat different from the "hydraulic" reaction of portland cement. In other words, the reaction characteristics of cement, "hydraulic", is a mechanism to form hydrates and cure when the components come into contact with water molecules, while the "potential hydraulic properties" of blast furnace slag are not solely eluted But the presence of irritants is necessary, which in turn promotes the reaction of blast furnace slag.

Immediately after the blast furnace slag comes into contact with water, Ca ions are eluted and an irregular oxide film with poor permeability is formed on the surface of the slag. The hydration reaction is difficult to proceed because this coating inhibits the penetration of water into the blast furnace slag particles and the dissolution of ions from the blast furnace slag particles. However OH on the surface of the slag by an alkaline stimulant ^- When the suction is coating (glass structure) are destroyed, the blast furnace slag from promoting the dissolution of _{SiO₂, Al 2 O₃, CaO,} MgO reaction begins. And once the reaction is started, the reaction can be continued because the alkaline component, which is eluted from the blast furnace slag itself, continuously maintains a high pH.

When the blast furnace slag is activated by the irritant, the CaO and SiO2 components of the blast furnace slag are eluted and hydrated to form silicate hydrate (CSH hydrate). Due to such a mechanism, the hydration reaction of blast furnace slag is usually slow to the reaction rate of Portland cement and causes the initial strength retardation of blast furnace slag-incorporated cured products. However, when the reaction starts, since the reaction is continuously performed over a long period of time, the long-term strength is superior to that of the Portland cement.

The present invention is a stimulant composition for promoting the initial hydration reaction of blast furnace slag as described above. In the past, alkaline stimulants such as NaOH, KOH and Ca (OH) ₂ were mainly used, but the present invention provides a stimulant composition of a novel ingredient.

The blast-furnace slag micropowder irritant composition according to the present invention (hereinafter referred to as a stimulant composition) includes dodecacalcium hepta-aluminate, anhydrous gypsum, tartaric acid and ethylenediaminetetraacetic acid (EDTA) .

Dodeca-calcium hepta-aluminate is represented by the general formula 12CaO · 7Al ₂ O _3, it may be simply represented by the C ₁₂ A _7. Dodeca calcium hepta aluminate is characterized by the rapid formation of acicular silicate hydrate of CaO-SiO ₂ -H ₂ O series upon reaction with water. Since the above hydration reaction is very rapid, the formation of an oxide film can be suppressed because the blast furnace slag fine powder meets with water and forms acicular hydrate on the surface of the blast furnace slag fine powder before the oxide film is formed on the surface. Also, in this embodiment, dodeca calcium hepta aluminate is formed into fine particles in the range of 2,000 ~ 3,000 Cm ² / g powder. If the powdery degree is high, the specific surface area of the powder capable of reacting with water is widened, so that the reactivity can be further improved. In this example, dodeca calcium heptaluminate is formulated in an amount of 65 to 73% by weight in the total irritant composition.

Anhydrous gypsum (CaSO ₄ ) is a sulfate stimulant widely used as an alkali stimulant of conventional blast furnace slag fine powders. When anhydrous gypsum reacts with water, sulfuric acid (SO ₄ ^2- ) can destroy the oxide film to activate the elution of calcium and aluminum ions in the blast furnace slag. Surplus sulfuric acid in anhydrous gypsum, which is not used to destroy the blast furnace slag film, forms a needle-like ettringite in the hardened body, thereby tightening the structure of the hardened body and increasing the compressive strength. In this embodiment, anhydrous gypsum is contained in an amount of 5 to 12% by weight in the whole stimulant. When the content of the gypsum is less than 5%, the film removing action is not smooth. When the content of the gypsum is more than 12% It is possible to exhibit the effect of weakening the strength of the cured body by being agglomerated in the cured body.

Tartaric acid is a kind of organic acid and has a weak acidity. The slag meets with the water and forms a vitreous coating (mainly slag Fe ₂ O ₃ The basic environment is advantageous when the components form a reaction. The tartaric acid acts to interfere with the formation of the vitreous coating by temporarily lowering the pH of the bar slag surrounding the acidic acid. It is also understood that the tartaric acid contains a large amount of OH ^- ions, and this hydroxide ion slows the reaction rate of the vitreous film formation. The tartaric acid is blended in the range of about 3 to 8% by weight in the total irritant composition. If the amount of the tartaric acid exceeds the above range, the hydration reaction of the blast furnace slag is slowed down, and if it is less than this range, the action of inhibiting the formation of the glassy film may not be smooth.

With respect to the formation of the glassy film of the slag, the dodecaheptaaluminate described above prevents the formation of the film by forming a needle-like structure on the surface of the slag before the film is formed. The anhydrous gypsum acted to destroy the glassy film formed by the sulfate ion in the slag, and the tartaric acid slowed the reaction to form the glassy film. Each of these materials has a different effect on the formation of the glassy coating on the slag surface.

In stimulant compositions according to the present invention, EDTA acts differently from the above substances. That is, EDTA selectively reacts with divalent iron ions, which is a main component of the vitreous coating formed on the surface of the slag, so-called chelate reaction to form complex ions. When the complex ion is formed, the chemical bond of the iron component, which is a main component of the vitreous coating, is changed, so that the glassy coating is broken and ions such as calcium and aluminum can be eluted from the slag. It can be understood that a kind of water channel through which water can pass through the slag film is formed, and calcium and aluminum react with water through the water channel to form an acridine zit in the acicular phase. In this embodiment, EDTA in the range of 10,000-20,000 Cm ² / g is used to promote the chelating reaction of EDTA. As described above, when the degree of the powder is high, the specific surface area is increased, so that the reaction rate is improved. In this embodiment, EDTA is formulated in the range of 15 to 22 wt.% In the total irritant composition.

Dodecaheptaaluminate and anhydrous gypsum can be used in powder form in the stimulant composition according to the present embodiment, and tartaric acid and EDTA can be used both in powder and liquid phase. When only dodeca hepta aluminate and anhydrous gypsum are used as the powder, the blending ratio between them is 70 to 80% by weight of dodecaheptaaluminate and 20 to 30% by weight of anhydrous gypsum. And between 60 to 70 wt% of EDTA (based on 292 g / mol of EDTA) between 30 to 40 wt% of tartaric acid (based on 15 g / mol of tartaric acid) and between tartaric acid and EDTA in the liquid phase. The liquid phase and the powder are not mixed in advance, and it is preferable to add them when blending the blast furnace slag cement together with water.

The present invention provides a blast furnace slag cement comprising the stimulant composition having the above-mentioned constitution. Blast furnace slag cement includes cement and irritant compositions. Here, the cement is usually mixed with the Portland cement, the blast furnace slag powder and the additive. The blast furnace slag fine powder in the cement is mixed at a ratio of 40 to 60% by weight. And the stimulant composition is mixed at a ratio of 3 to 10% by weight with respect to the whole cement.

The inventors of the present invention conducted a physical property test by forming a concrete containing blast furnace slag cement according to the present invention in order to examine the effect of blast furnace slag cement mixed with a stimulant composition.

In concrete, Portland cement (OPC) and blast furnace slag powder (S / P) were mixed with cement. Usually, Portland cement and blast furnace slag were mixed with the same specific gravity of 1: 1. The detailed mixing ratio of concrete is as shown in [Table 1].

[Table 1]

Referring to Table 1, Sample No. 1 is a control sample without using the stimulant composition according to the present invention, Sample No. 2 is a powder sample (D-AD) using dodeca hepta aluminate and anhydrous gypsum, TTA and EDTA use a stimulant composition mixed with a liquid phase (L-AD). Sample No. 2 is an example using 5% of a stimulant composition relative to cement (OPC + slag fine powder (S / P)), and Sample No. 3 is an example using 10% of a cement-based stimulant composition. The remaining aggregate and water / cement ratio are the same in all three samples. And 68% by weight of dodecaheptaaluminate, 9% by weight of anhydrous gypsum, 5% by weight of tartaric acid and 18% by weight of EDTA based on 100% of the stimulant composition as a whole.

In the experiment, the compressive strengths of concrete, 3 days, 7 days and 28 days were determined. The results are shown in [Table 2] below.

[Table 2]

When the compressive strength of the control sample (1) is taken as 100%, the strength of the mixture of 5% and 10% of the stimulant composition is 3 days, 7 days, 28 days Which is higher than that of the control sample. Particularly, the problem of the initial strength drop which is pointed out as a weak point of the blast furnace slag cement is drastically improved. That is, the compressive strength of the second sample was 16% and that of the third sample was 21% higher than that of the first control sample at 3 days compressive strength. At 28 days strength, the increase rate of the strength compared to the control sample was not as large as 3 days but was about 10% higher. It was confirmed that the case where 10% of the stimulant composition was used was more advantageous in terms of compressive strength than the case where 5% of the stimulant composition was used. All three samples showed the same slump.

Meanwhile, the stimulant composition according to the present invention can be produced only by powder, unlike the previous experiment. Experimental examples and results in the case of using the powdery stimulant composition are shown in [Table 3] and [Table 4], respectively.

[Table 3]

[Table 4]

Referring to [Table 3], the blending ratio between the sample (1) without the irritant composition and the sample (2) using the powdered irritant composition is shown. Except for the condition of the stimulant composition, all the conditions are the same as in the previous experiment.

As shown in Table 4, when the powder type was used, the strength was improved by 31% at the 3 day compressive strength compared with the control sample, and the strength was increased by 19% at 28 days. In case of using as powder type, the slump was increased as compared with the control experiment. However, since the increase is not large, there is no significant difference in the fluidity and workability of concrete.

The results in Table 4 are the result of curing concrete at 20 ° C, and the researchers added an additional curing test at 5 ° C in preparation for winter. The mixing ratio of the samples prepared for the experiment and the experimental results are shown in [Table 5] and [Table 6].

[Table 5]

[Table 6]

As shown in [Table 4] and [Table 6], compressive strength was significantly increased as a result of curing at 5 ° C compared with the concrete curing at 20 ° C. Of course, it is a natural phenomenon that the actual compressive strength is lowered when the temperature is low, at 19.3 MPa when cured at 20 ° C and at 6.7 MPa when cured at 5 ° C, based on the compressive strength at 3 days. However, it is important to compare with control samples. When the stimulant composition according to the present invention is used at the same temperature condition as the control specimen, the increase rate of the compressive strength is high, which means that the cement composition according to the present invention has a great advantage in the winter construction.

As described above, the blast furnace slag cement powder composition according to the present invention and the blast furnace slag cement using this composition show that the compressive strength, particularly the initial compressive strength, is higher than that of the general blast furnace slag cement without using the irritant composition . These results indicate that the four components of the irritant composition according to the present invention, i.e., dodecaheptaaluminate, anhydrite, tartaric acid and EDTA, inhibit the formation of the blast furnace slag film itself, slow down the reaction rate, And to form a water channel.

The use of the irritant composition according to the present invention is economical but it is expected that the blast furnace slag fine powder which is used as the main material of the cement binder due to the decrease in the initial compressive strength can be used more positively.

The scope of protection of the present invention is not limited to the description and the expression of the embodiments explicitly described in the foregoing. It is again to be understood that the present invention is not limited by the modifications or substitutions that are obvious to those skilled in the art.

Claims (6)

Wherein the blast furnace slag powder is added in an amount ranging from 3 to 10% by weight based on the entire blast furnace slag cement composition containing 40 to 60% of blast furnace slag fine powders to stimulate the blast furnace slag fine powder,
65 to 73% by weight of dodecacalcium hepta-aluminate, 5 to 12% by weight of anhydrous gypsum, 3 to 8% by weight of tartaric acid and 15 to 22% by weight of ethylenediaminetetraacetic acid (EDTA) ≪ / RTI >
Wherein the powder of the dodeca calcium hepta aluminate is in the range of 2,000 to 3,000 Cm ² / g, and the powder of the EDTA is in the range of 10,000 to 20,000 Cm ² / g. delete delete The method according to claim 1,
The tartaric acid and EDTA are liquid,
Wherein said anhydrous gypsum and dodeca calcium heptaaluminate are in powder form. Cement comprising blast furnace slag fine powder and ordinary portland cement and a stimulus composition for promoting the activity of said blast furnace slag fine powder,
The blast furnace slag fine powder is blended in a range of 40 to 60 wt%
Wherein the stimulant composition is the blast furnace slag fine powder stimulant composition according to claim 1 or claim 4. 6. The method of claim 5,
The blast furnace slag cigarette composition according to claim 1, wherein the blast furnace slag powder composition is blended in an amount of 3 to 10% by weight.

Images